Question

A stone is dropped from the top of a 40 m high tower. Calculate its speed after 2 s. Also find the speed with which the stone strikes the ground.​

Answer 1

Given that,

Height = 40 m

Time t =2 sec

We know that,

$\small\red{v = u + gt\\ v = 0 + 9.8\times2\\ v = 19.6m/s}$

The speed of stone is 19.6 m/s

Now, the speed with which the stone strikes the ground

$\small\red{v^2 = u^2 + 2gs\\ v^2 = 0+2\times9.8\times40\\ v^2 = 784\\ v= 28m/s}$

Hence, the speed with which the stone strikes the ground is 28 m/s.

♥️

Answer 2

$\huge\sf\underline\red{Solution}$

Given,

Height = 40 m

Time t =2 sec

We know that,

v=u+gt

v=0+9.8×2v=0+9.8×2

v=19.6m/s v=19.6m/s

The speed of stone is 19.6 m/s

Now, the speed with which the stone strikes the ground

v²=u² + 2gs

v²=0+2×9.8×40 v2=0+2×9.8×40

v²=784

v=28m/s

Hence, the speed with which the stone strikes the ground is 28m/s